Physik-Kolloquium: Molecular movies using X-ray lasers

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Physik-Kolloquium: Molecular movies using X-ray lasers

Tuesday, 20. June 2017 // 15.15 - 17.00

Institut für Physik der HU

Newtonstraße 15, 12489 Berlin
Lise-Meitner-Haus, Christian-Gerthsen-Hörsaal

Herr Prof. John C. H. Spence FRS (Department of Physics, Arizona State University, USA) spricht zum Thema "Molecular movies using X-ray lasers".

Abstract: It had always been supposed that the radiation dose needed to image a molecule at atomic resolution would destroy it. The ability to "out-run" radiation damage, by collecting enough elastic X-ray scattering in the femtoseconds before a photoelectron cascade destroys a protein, has transformed this field. The recently-invented X-ray laser (such as the EuXFEL in Hamburg) packs 1E12 photons into a 10 fs pulse, allowing damage-free snapshots and movies of molecular machines at work. I’ll give examples from the work of researchers in our NSF BioXFEL university consortium in the USA, including a pump-probe movie of the cis-trans isomerisation reaction, the first event in human vision, when one photon is absorbed by a protein at the back of the eye. We see that, as Feynman said "Life consists of the wiggling and jiggling of atoms". The physics of the SASE-mode pulsed laser, the sample delivery systems, solutions to the phase problem, and progress imaging single viruses (with one virus per shot) will all be reviewed. Preliminary results will also be shown from our new Mixing Jet sample injectors, for imaging chemical reactions such the reaction of a substrate chemical solution with an enzyme (catalyst). Prospects for out-running damage using femtosecond MeV electron pulses will be reviewed if time allows.

Reference: J. C. H. Spence. "Imaging Protein Dynamics" in Advanced in Imaging and Electron Physics Vol 200. (2017)